1. Field of the Invention
This invention relates to new chemical compositions and to lubricating oil compositions containing these compositions. More particularly, it relates to a novel class of chemical compositions which in part act both as rust and corrosion inhibitors and dispersants in lubricating oils.
2 Description of the Prior Art
The prior art has taught the need for efficient rust inhibitors in lubricating oils. The need is particularly prevalent in engines which are infrequently operated or which are subject to extended storage in humid climates, because these engines experience excessive rusting of cylinder walls, wrist pins and other polished working surfaces. Under such conditions moisture accumulates within the engine, penetrates the lubricating film and attacks ferrous surfaces. This attack is aggravated by residues of chlorine and bromine compounds produced in the combustion of gasolines containing tetraethyl lead and scavenging agents such as ethylene dibromide.
Any such deterioration results in the accumulation of products which agglomerate to form sludge and varnish-like deposits. It is highly useful to delay this agglomeration by an additive which disperses such products as they are formed.
Certain alkyl and alkenyl succinic anhydrides, acids, and various salts thereof have been proposed as ashless or low ash rust inhibitors for motor lubricants, e.g., such materials are described in U.S. Pat. No. 3,381,022. Unfortunately, these compounds, although having rust inhibiting properties fail to usefully disperse the corrosion products which do inevitably form over the operational lifetime of the device in which the lubricant is used or the fuel is converted to mechanical energy.
Accordingly, there has been a continuing search for new and improved economical, low ash rust inhibitors which are compatible with other lubricating oil additives and do reduce corrosion and/or sludge formation.